| A: | 16O + 16O18O 16O16O18O | (1) |
| B: | 18O + 16O16O 18O16O16O | (2) |
| S: | 16O + 18O16O 16O18O16O | (3) |
| I: | 18O + 16O16O 16O18O16O | (4) |
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